Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... A new type of double picket-fence porphyrin, bearing pyrimidine rings at the meso-positions was prepared from the corresponding pyrimidine-5-aldehydes using either Rothemund or McDonald condensation reactions. ... Double picket fence porphyrins were prepared starting from ...